Confluence is a critical property of computational systems which is related with determinism and non ambiguity and thus with other relevant computational attributes of functional specifications and rewriting system as termination and completion. Several criteria have been explored that guarantee confluence and their formalisations provide further interesting information. This talk will discuss topics related with the formalisation of confluence properties in the prototype verification system PVS. Syntactic criteria such as avoiding overlapping of rules as well as linearity of rules have been used as a discipline of functional programming which avoids ambiguity. In the context of term rewriting systems, well-known results such as Newman’s Lemma [7], Rosen’s Confluence of Orthogonal term rewriting systems [9] as well as the famous KnutBendix(-Huet) Critical Pair Theorem [6, 5] are of great theoretical and practical relevance. The first one, guarantees confluence of Noetherian and locally confluent abstract reduction systems; the second one, assures confluence of orthogonal term rewriting systems, that are systems which avoid ambiguities generated by overlapping of their rules and whose rules do not allow repetitions of variables in their left-hand side (i.e., left-linear); and, the third one provides local confluence of term rewriting systems whose critical pairs are joinable. Formalisations of these confluence criteria provide valuable and precise data about the theory of rewriting (cf. [4], [3], [8]). Several aspects that arise from these formalisations are of great relevance for the formal discussion about how these properties should be adequately ported to different computational contexts such as the nominal approach of rewriting (cf. [1] [2]).
{"title":"Program committee","authors":"Terry V. Benzel","doi":"10.1109/IOLTS.2005.58","DOIUrl":"https://doi.org/10.1109/IOLTS.2005.58","url":null,"abstract":"Confluence is a critical property of computational systems which is related with determinism and non ambiguity and thus with other relevant computational attributes of functional specifications and rewriting system as termination and completion. Several criteria have been explored that guarantee confluence and their formalisations provide further interesting information. This talk will discuss topics related with the formalisation of confluence properties in the prototype verification system PVS. Syntactic criteria such as avoiding overlapping of rules as well as linearity of rules have been used as a discipline of functional programming which avoids ambiguity. In the context of term rewriting systems, well-known results such as Newman’s Lemma [7], Rosen’s Confluence of Orthogonal term rewriting systems [9] as well as the famous KnutBendix(-Huet) Critical Pair Theorem [6, 5] are of great theoretical and practical relevance. The first one, guarantees confluence of Noetherian and locally confluent abstract reduction systems; the second one, assures confluence of orthogonal term rewriting systems, that are systems which avoid ambiguities generated by overlapping of their rules and whose rules do not allow repetitions of variables in their left-hand side (i.e., left-linear); and, the third one provides local confluence of term rewriting systems whose critical pairs are joinable. Formalisations of these confluence criteria provide valuable and precise data about the theory of rewriting (cf. [4], [3], [8]). Several aspects that arise from these formalisations are of great relevance for the formal discussion about how these properties should be adequately ported to different computational contexts such as the nominal approach of rewriting (cf. [1] [2]).","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114236464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-17DOI: 10.1109/CONATEL.2011.5958675
F. Pereira
Video compression is a key technology in the current multimedia services and applications landscape, which has been evolving to provide increasingly powerful user experiences. This evolution has continuously enlarged the set of networks and terminals able to provide video enabled experiences, as well as continuously improved the quality of the experiences provided for important services and applications, ranging from digital TV, and mobile and Internet video streaming to video games and Blu-ray discs. This evolution and its market impact is strongly determined by the set of video compression standards developed along the years since these standards allowed to provide easier interoperability and reduce the deployment costs. This paper reviews the current status quo in video compression, as well as the main trends, with special emphasis on video compression standards, considering their particular influence on the deployment success of this technology.
{"title":"Video compression: An evolving technology for better user experiences","authors":"F. Pereira","doi":"10.1109/CONATEL.2011.5958675","DOIUrl":"https://doi.org/10.1109/CONATEL.2011.5958675","url":null,"abstract":"Video compression is a key technology in the current multimedia services and applications landscape, which has been evolving to provide increasingly powerful user experiences. This evolution has continuously enlarged the set of networks and terminals able to provide video enabled experiences, as well as continuously improved the quality of the experiences provided for important services and applications, ranging from digital TV, and mobile and Internet video streaming to video games and Blu-ray discs. This evolution and its market impact is strongly determined by the set of video compression standards developed along the years since these standards allowed to provide easier interoperability and reduce the deployment costs. This paper reviews the current status quo in video compression, as well as the main trends, with special emphasis on video compression standards, considering their particular influence on the deployment success of this technology.","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121918485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-17DOI: 10.1109/CONATEL.2011.5958662
A. C. Gordillo, Kui Zhou
In this paper, we analyze the current issues for designing a communications system among implant and on-body nodes employing ultra wideband (UWB) technology. As a result, we propose a modulation scheme ad-hoc for this environment that besides being suitable for this propagation channel, it allows to employ antenna diversity on the on-body nodes. Antenna diversity permits to improve signal to noise ratio and avoid using transmission diversity, which limits the exposition of human tissue to electromagnetic radiation.
{"title":"Design considerations for implant — On-body UWB communication for medical applications","authors":"A. C. Gordillo, Kui Zhou","doi":"10.1109/CONATEL.2011.5958662","DOIUrl":"https://doi.org/10.1109/CONATEL.2011.5958662","url":null,"abstract":"In this paper, we analyze the current issues for designing a communications system among implant and on-body nodes employing ultra wideband (UWB) technology. As a result, we propose a modulation scheme ad-hoc for this environment that besides being suitable for this propagation channel, it allows to employ antenna diversity on the on-body nodes. Antenna diversity permits to improve signal to noise ratio and avoid using transmission diversity, which limits the exposition of human tissue to electromagnetic radiation.","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131444801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-17DOI: 10.1109/CONATEL.2011.5958655
N. C. L. Valdivia, G. M. Fernández
In some developing countries, like Peru, optical transport networks are not widely deployed, mainly because of economical factors and geographical difficulties. Its topology has a fishbone-like structure, and it may not need powerful all-optical multicast nodes in order to attend multicast demands. Also, traffic demands may not occupy all the wavelength capacities, which make traffic grooming a necessary capability for saving bandwidth. In the present work we propose an optical node capable of performing multicast routing tasks at traffic grooming level. The node's architecture has been based on two previous works: the 2-Split-Tap-and-Continue (2-STC) node (a multicast capable node with a simple structure, constrained to binary-splitting, but efficient regarding the use of power levels and the number of elements used), and the Stop-and-Go (S/G) Light Tree node (a multicast grooming capable node that uses a labeling technique based on FSK modulation, allowing multicast requests to be routed at the optical level). In this sense, the proposed node improves the use of the optical power, waste of bandwidth and delay, taking advantage of the physical distribution presented in this particular fishbone-like network. Several simulations have been done and results show these assessments.
{"title":"2-STCg optical multicast traffic grooming node for the fishbone-like Peruvian WDM core network","authors":"N. C. L. Valdivia, G. M. Fernández","doi":"10.1109/CONATEL.2011.5958655","DOIUrl":"https://doi.org/10.1109/CONATEL.2011.5958655","url":null,"abstract":"In some developing countries, like Peru, optical transport networks are not widely deployed, mainly because of economical factors and geographical difficulties. Its topology has a fishbone-like structure, and it may not need powerful all-optical multicast nodes in order to attend multicast demands. Also, traffic demands may not occupy all the wavelength capacities, which make traffic grooming a necessary capability for saving bandwidth. In the present work we propose an optical node capable of performing multicast routing tasks at traffic grooming level. The node's architecture has been based on two previous works: the 2-Split-Tap-and-Continue (2-STC) node (a multicast capable node with a simple structure, constrained to binary-splitting, but efficient regarding the use of power levels and the number of elements used), and the Stop-and-Go (S/G) Light Tree node (a multicast grooming capable node that uses a labeling technique based on FSK modulation, allowing multicast requests to be routed at the optical level). In this sense, the proposed node improves the use of the optical power, waste of bandwidth and delay, taking advantage of the physical distribution presented in this particular fishbone-like network. Several simulations have been done and results show these assessments.","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128605831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-17DOI: 10.1109/CONATEL.2011.5958659
C. Fernandes, J. Boavida, J. Morgado
A time domain model based on matricial techniques is used to study the large-signal dynamics in an asymmetric three Phase-Shift DFB laser structure, which has been optimized in a previous work of the authors near threshold and been referred as being potentially stable for single longitudinal mode operation in the high power regime. These models, generally designated as dynamic transfer-matrix models, are very flexible and are indispensable for a proper evaluation of the device performance.
{"title":"Analysis of Phase-Shift DFB lasers using the dynamic transfer-matrix-method","authors":"C. Fernandes, J. Boavida, J. Morgado","doi":"10.1109/CONATEL.2011.5958659","DOIUrl":"https://doi.org/10.1109/CONATEL.2011.5958659","url":null,"abstract":"A time domain model based on matricial techniques is used to study the large-signal dynamics in an asymmetric three Phase-Shift DFB laser structure, which has been optimized in a previous work of the authors near threshold and been referred as being potentially stable for single longitudinal mode operation in the high power regime. These models, generally designated as dynamic transfer-matrix models, are very flexible and are indispensable for a proper evaluation of the device performance.","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123039099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-17DOI: 10.1109/CONATEL.2011.5958671
Michal Mrajca, Z. Brabec
It is necessary for any telecommunication provider to introduce new products or changes of existing products as quickly and as often as possible. It helps them to stay ahead of competition. To achieve that they have to have an effective and efficient inner business processes. Almost every conscious company measure, assess and adjust its processes. This paper describes the Change Management process within New Generation Operation Support System (NGOSS) of one Czech telecommunication service provider.
{"title":"Probabilistic description of the NGOSS Change Management process","authors":"Michal Mrajca, Z. Brabec","doi":"10.1109/CONATEL.2011.5958671","DOIUrl":"https://doi.org/10.1109/CONATEL.2011.5958671","url":null,"abstract":"It is necessary for any telecommunication provider to introduce new products or changes of existing products as quickly and as often as possible. It helps them to stay ahead of competition. To achieve that they have to have an effective and efficient inner business processes. Almost every conscious company measure, assess and adjust its processes. This paper describes the Change Management process within New Generation Operation Support System (NGOSS) of one Czech telecommunication service provider.","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114504077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-17DOI: 10.1109/CONATEL.2011.5958668
J. Molinero, Amaya Jiménez, Eduardo Martínez-Enríquez, F. Díaz-de-María
The most recent video coding standards are usually based on a rate-distortion optimization (RDO) process that has been formulated in terms of an unconstrained Lagrangian optimization. The RDO provides outstanding results in exchange for a high computational cost, especially for the Inter frames, which require a computationally heavy motion estimation (ME) process. In particular, for H.264/AVC, this RDO process allows selecting both the MB partition size and the motion vector. However, as the optimum procedure is not feasible for computational reasons, the ME process uses a simplified rate-distortion (RD) cost function. Therefore, two RDO processes are involved, one for selecting the MB partition size and one for ME. Both RDO processes rely on an Lagrangian formulation and, for practical purposes, the corresponding Lagrangian parameters are related by a simple, experimentally obtained relationship. In this paper, some evidences of the weaknesses of such a relationship between the two Lagrangian parameters are given and a simple effective procedure to improve the R-D encoding performance is proposed according to such weaknesses. The proposed method has been comparatively evaluated with respect to one recently published method, showing significant average performance improvements, above 0.4 dB in terms of PSNR.
{"title":"On the optimal Lagrangian parameter for motion estimation: A low-cost and effective method for improving video coding performance","authors":"J. Molinero, Amaya Jiménez, Eduardo Martínez-Enríquez, F. Díaz-de-María","doi":"10.1109/CONATEL.2011.5958668","DOIUrl":"https://doi.org/10.1109/CONATEL.2011.5958668","url":null,"abstract":"The most recent video coding standards are usually based on a rate-distortion optimization (RDO) process that has been formulated in terms of an unconstrained Lagrangian optimization. The RDO provides outstanding results in exchange for a high computational cost, especially for the Inter frames, which require a computationally heavy motion estimation (ME) process. In particular, for H.264/AVC, this RDO process allows selecting both the MB partition size and the motion vector. However, as the optimum procedure is not feasible for computational reasons, the ME process uses a simplified rate-distortion (RD) cost function. Therefore, two RDO processes are involved, one for selecting the MB partition size and one for ME. Both RDO processes rely on an Lagrangian formulation and, for practical purposes, the corresponding Lagrangian parameters are related by a simple, experimentally obtained relationship. In this paper, some evidences of the weaknesses of such a relationship between the two Lagrangian parameters are given and a simple effective procedure to improve the R-D encoding performance is proposed according to such weaknesses. The proposed method has been comparatively evaluated with respect to one recently published method, showing significant average performance improvements, above 0.4 dB in terms of PSNR.","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121633755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-17DOI: 10.1109/CONATEL.2011.5958667
Miguel A. Ferrer, A. Morales, J. Vargas
Recently, several papers have proposed pseudo dynamic methods for automatic handwritten signature verification. Each of these papers uses texture measures of the gray level signature strokes. This paper explores the usefulness of local binary pattern (LBP) and local directional pattern (LDP) texture measures to discriminate off-line signatures. A comparison between several texture normalizations is made so as to look for reducing pen dependence. The experiments conducted with MCYT off-line and GPDS960Graysignature corpuses show that LDPs are more useful than LBPs for automatic verification of static signatures. Additionally, the results show that the LDP codes of the contour are more discriminating than the LDPs of the stroke interior, although their combination at score level improves the overall scheme performance. The results are obtained by modeling the signatures with a Support Vector Machine (SVM) trained with genuine samples and random forgeries, while random and simulated forgeries have been used for testing it.
{"title":"Off-line signature verification using local patterns","authors":"Miguel A. Ferrer, A. Morales, J. Vargas","doi":"10.1109/CONATEL.2011.5958667","DOIUrl":"https://doi.org/10.1109/CONATEL.2011.5958667","url":null,"abstract":"Recently, several papers have proposed pseudo dynamic methods for automatic handwritten signature verification. Each of these papers uses texture measures of the gray level signature strokes. This paper explores the usefulness of local binary pattern (LBP) and local directional pattern (LDP) texture measures to discriminate off-line signatures. A comparison between several texture normalizations is made so as to look for reducing pen dependence. The experiments conducted with MCYT off-line and GPDS960Graysignature corpuses show that LDPs are more useful than LBPs for automatic verification of static signatures. Additionally, the results show that the LDP codes of the contour are more discriminating than the LDPs of the stroke interior, although their combination at score level improves the overall scheme performance. The results are obtained by modeling the signatures with a Support Vector Machine (SVM) trained with genuine samples and random forgeries, while random and simulated forgeries have been used for testing it.","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125004218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-05-17DOI: 10.1109/CONATEL.2011.5958673
T. R. B. Oliveira, E. Ursini, V. Timóteo
Mobile devices that are permanently connected to IP networks are prone to have higher energy consumptions because unsolicited packets also force the device to move to a state where the consumption is higher. We consider a simplified model for the energy consumption based on the average consumptions in the different states and the time the device stays in each state. We perform discrete event simulations to obtain the energy consumption for different traffic scenarios and the simulation results are then fitted with simple models. We find that they give a relatively good description of the energy consumption behavior as a function of the T2 timer. Also, our results are consistent with measurements of the energy consumption for a mobile device connected to 3G networks with high or low data traffic profile.
{"title":"Simulation inspired model for energy consumption in 3G always-on mobiles","authors":"T. R. B. Oliveira, E. Ursini, V. Timóteo","doi":"10.1109/CONATEL.2011.5958673","DOIUrl":"https://doi.org/10.1109/CONATEL.2011.5958673","url":null,"abstract":"Mobile devices that are permanently connected to IP networks are prone to have higher energy consumptions because unsolicited packets also force the device to move to a state where the consumption is higher. We consider a simplified model for the energy consumption based on the average consumptions in the different states and the time the device stays in each state. We perform discrete event simulations to obtain the energy consumption for different traffic scenarios and the simulation results are then fitted with simple models. We find that they give a relatively good description of the energy consumption behavior as a function of the T2 timer. Also, our results are consistent with measurements of the energy consumption for a mobile device connected to 3G networks with high or low data traffic profile.","PeriodicalId":197632,"journal":{"name":"CONATEL 2011","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115105135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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